Can the same project be modified in both Sencha Designer and any other Tool?

Based on Sench Conference Designer Vide I assumed that the same project can be modified using both Sencha Designer Tool and also any other Development Tool of choice like Visual Studio, Aptana, Notepad, etc.
We did a simple test: created a project with a single from in Designer. Form has a single button. Then we opened the source in Notepad and modified button label as

{
xtype: 'button',
itemId: 'mybutton',
text: 'Modified'
}

When you run application you see a new 'Modified' text.
But if you open the same project in Designer, it still displays original Button text.
We found that label is also stored in the metadata files that developers are not supposed to modify. And this is why the old label is displayed in Designer.